Tuning apparatus for radio receivers



April 11, 1939. A, E. GERSCH TUNING APPARATUS FOR RADIO RECEIVERS FiledAug. 21, 1937 5 Sheets-Sheet l 7 Ta/ ram Lido hi". Game/z,

April 11, 1939. A: E. GERSCH TUNING APPARATUS FOR RADIO RECEIVERS FiledAug. 21, 1937 v 5 Sheets-Sheet 2 ,amzaz,

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MEN Q April 11, 1939. A. E. GERSCH 2,153,865

TUNING APPARATUS FOR RADIO RECEIVERS Filed Aug. 21, 1937 Sheets-Sheet 3Y I l! 25476 47 42 520M235:- 624050/4 l 'Ge ac/z,

, April 11, 1939. A. E. GERSCH TUNING APPARATUS FOR RADIO RECEIVERS 5Sheets-Sheet 4 Pawerl/ha Filed Aug. 21, 1957 (idol obi? (f 671561 4April 11, 1939. A. E. GERSCH I TUNING APPARATUS FOR RADIO RECEIVERSFiled' Aug. 21, 1957 5 Sheets-Sheet 5 I daaZ/afz E Ga e/z wwgm PatentedApr. 11, 1939 TUNING APPARATUS FOR, RADIO RECEIVERS Adolph E. Gel-sch,Chicago, Ill., asslgnor to Stewart-Warner Corporation, Chicago, 111., a

corporation of Vir Application August 21, 1937, Serial No. 180,238

- ,16 Claims. (Cl. 250-40) This invention relates .to new and improvedtuning apparatus for radio receivers and more particularly to meanswhereby a. radio receiving set may be automatically tuned to a desiredfrequency by a selective manual control.

The present-day radio receiver comprises as its .tuning element amultiple unit variable condenser which varies the capacity in aplurality of circuits simultaneously by means of the rotation of asingle shaft. The usual tuning control for variation of frequencycomprises a rotatable knob which 'serves either directly or through aspeed reduction means to rotate the condenser shaft. A calibrated dialis driven from the condenser shaft so that the user may observe thetuning operation and locate the desired station frequency.

While some such dials carry the radio station designations to assist intuning, this is generally impractical due to the large number of suchstationsand due to the fact that such a dial becomes obsolete withchanges of frequencies or of station call letter assignments. When thedial is merely calibrated in frequencies, it is necessary for theuser'to know the operating frequency of the desired station and toobserve the dial carefully and to adjust it slowly when near the desiredfrequency. The large number of stations on the air renders it diilicultto memorize the frequencies of all stations which it may be desired toreceive from time to time.

It is an object of the present invention to provide tuning apparatus forradio receivers whereby the apparatus may be easily and rapidly tuned toa desired station frequency.

It is a further object to provide such tuning apparatus provided with apluralityof manually operable controls, each of which serves to tune theapparatus to an indicated station.

It is also an object to provide such apparatus wherein the automaticcontrols may each be easily and quickly adjusted to serve to tune theset to a desired frequency.

It is an additional object to provide a construction in which thisadjustment may be car- ,ried out by unskilled persons without knowledgeof the details of the mechanism.

It is a further object to provide such an ap-' paratus for the controlof a tuning device op- It is also an object to provide apparatus of cthis character which may be readily disconnected to permit the usualcontinuous manual adjustment of the tuning device.

It is an additional object to provide apparatus of this type which willautomatically silence the radio receiver during the automatic adjustmentof the tuning device.

It is a further object to provide such apparatus which automaticallycuts into and out of circuit an automatic frequency control circuit atpredetermined portions of the cycle of operation.

It is also an object to provide anapparatus which will automaticallycontrol indicating means to show to the user whether the apparatus isadjusted for automatic or continuous manual operation.

It is an additional object to provide an apparatuswf this character, inwhich the resumption of manual tuning by the user automatically adjuststhe mechanism for manual tuning.

Other and further objects will appear as the description proceeds.

I have shown certain preferred embodiments of myinvention in theaccompanying drawings, in which- Figure l is a plan view of the controlapparatus in position for manual operation, with parts broken away forthe sake of clearness;

Figure 2 is a front view of the apparatus of Figure 1, with the dial orindicating mechanism associated therewith;

Figure 3 is a fragmentary view of a portion of the left end of Figure 1;

Figure 4 is a fragmentary view showing a control cam and associatedclamping cup assembled on the shaft;

Figure 5 is a fragmentary section of the construction of Figure 4;

Figure 6 is an end elevation taken from the right end of Figure 1;

Figure 'l is a sectional elevation taken on the line 'l'! of Figure l;

Figure 8 is a schematic diagram showing the electrical connections andswitches actuated during the operation of the mechanism, with the clutchin automatic control position;

Figure 8a is a schematic diagram showing the cam and cam bar actuatingthe switch cam of Figure 8;

Figure 9 is a fragmentary view, on an enlarged scale and partly insection, showing the cam disc clamping mechanism;

Figure 10 is a fragmentary view of the clamping mechanism, as seen fromthe right of Figure 9;

Figure '11 is a cross section taken on the line ll-IlofFigureQ;

Figure 12 is an exploded perspective view of the parts of the clampingmechanism; and

Figure 13 is a fragmentary section showing the friction brake mechanism.

Referring first to Figures 1, 2, 6 and 7, the mechanism is mounted in asheet metal frame or housing having a U-shaped front member II and aflat rear closure member I2. As shown in Figure 2, this supportingstructure II and I2 is mounted on a radio receiver chassis I3 by meansof the brackets I4. The chassis I3 carries the dial I8 and indicator I1by means of standard I5. This indicator I1 is driven by means of cableI8 passing over pulleys I9 and 20 and driven by the pulley 2|, which isdriven by means of the gear 22 from the automatic drive mechanism. Thegear 22 is driven by gear IOI which is secured to the shaft I02 alsocarrying the gear I03. The gear I03 meshes with the crown gear I04 whichis carried by the' end of the main driven shaft 23. The details of thisdial and indicating construction form no part of the present inventionand need not be described in further detail.

The automatic control mechanism includes the shaft 23 which extendslongitudinally of the housing member I I and is rotatably carried by thebrackets 31 and 38 secured to the housing. As shown in Figure 3, thisshaft 23 is provided with the longitudinally extending keyway 24. Thestop disc 25 is keyed to the left end of the shaft, and this disc 25carries the stop lug 28 which en-, gages the stops 21 and 28 at eitherend of an arc of rotation of 180. Stops 21 and 28 are formed by theupper edges of inturned lugs which are bent in on the bracket member 31.

The shaft 23 supports a plurality of control cam discs 3! which arerotatably carried by the shaft. Between each adjacent pair of controlcams 3I are located a pair of clamping cups 32 which are oppositelyfaced so that the flat flange 33 of each cup engages a cam disc 3|. Thisis best shown in Figure 5. The clamping cups 32 are all keyed to theshaft 23 in such manner that they may freely slide axially of the shaft,but are constrained to rotate with the shaft. A loeating disc 34 issecured to the shaft 23 adjacent the left face of the bracket 31 by setscrew 35,

as shown in Figure 1.

Adjacent the inner face of the bracket 38 the locking cup 30 is keyed tothe shaft 23, the righthand face of the cup having a plurality of cammeans 36 formed thereon. The cup 39 is rotatably carried on the shaft 23adjacent the cup 35 and is provided with cam faces 40 coacting with thecams 36 on the cup 35. The cup 39 serves as a bearing for the shaft 23and itself fits in a circular opening I05 in the supporting bracket 38.Outside the bracket 38, the cup 39 has the gear I08 secured to it, abearing washer I01 being between the gear I06 and the outer face a ofthe bracket 38. The gear I06 has the struck up lug I08 on its outerface. The spring I09 is held against the outer face of the gear I08 bythe thrust plate H0 which is keyed to shaft 23 to rotate therewith. Thethrust plate H0 is held against longitudinal movement along the shaft 23to the right by the pin III which passes through the shaft. The springI09 has a raised portion II2 adapted to latch over the lug I08 on thegear I08 in one position of the parts, as will be explained in detail inconnection with the operation of the apparatus.

As shown in Figure '1, the frame, formed of members II and I2, carries aplurality of push buttons 4i, each of which is secured to the front endof a station-selecting slide 42. The buttons 4| are in two rows in orderto reduce the required linear extent of the control device. This isaccomplished by alternately turning upwardly and downwardly the offsetforward portion 43 of the station-selector slides, the rear portions ofall slides being in the same plane. Each slide is provided withdownwardly extending detents 44 which have sloping rear faces 45. Thedetent latch 48 is carried by the shaft 41 and has a rear portion 48engaging the sloping surfaces 45 of the detents. The slides 42 are alsoprovided with the upwardly extending clutch bar lugs 49 engaging the,clutch bar 50 which is carried on shaft 5|. The rear portion 52 of eachslide 42 passes through a slot in the rear frame member I2. The clutchbar 50 is held against the rear faces of the lugs 49 by means of thespring 55, the free end of which is secured at 56 to the bracket 38.

The shaft 51 carries a plurality of pawls 58 which are freely rotatableabout the shaft. The lower portion of each pawl is provided with aturned up extension 59 which engages the front portion ofthe upwardlyextending clutch bar lug 49. The forward portion 60 of the lower end ofeach pawl has connected thereto a tension spring 8|, the other end ofwhich is connected at 82 to an upper extension of the lug 49 of thecorresponding key slide 42.

The cam bar 63 is pivotally supported on the shaft 51, the bar extendinglongitudinally of the assembly. This bar 63 has its upper edge extendingagainst the front face of the row of pawls 58. The upper extension 65 onthe cam bar carries the arm 66 which in turn supports the switch cam 81.This switch cam 81 has low portions 88 and 89 and high portions 10 andH. The cam bar 83 is held in position against the pawls by means of thetension coil spring 12, one end of which is connected to the cam bar andthe other end of which is connected to the rear frame number I2.

The switch assembly 13 is supported by bracket II4 from frame member I2and is provided with nine contact carrying current-conducting springmembers which are insulated from each other. The outermost pair H5 andH8 of these contact springs are connected in an automatic frequencycontrol circuit, as best shown in Figure 9 and are in parallel withcontacts in another switch assembly II1 operated by the clutchmechanism. The next pair of these conducting spring members 14 and 15are connected in a circuit such that when their contacts engage eachother the grids of audio amplification tubes are short circuited so thatthe set is silenced. In other words, these two contacting springs serveto open and close the mute control circuit of the set.

The next pair of contacts 11 and 18 are connected in the power circuitof the automatic control actuating motor 19. The free end of spring H8is turned inwardly at Hi! to engage an insulating strip I20 held againstthe face of spring 14. The free end of spring 15 is turned inwardly atto engage an insulating strip 8| held against the face of spring 18.Springs 15 and H8 are normally biased so as to break their contacts withsprings 14 and H5, but due to the extensions 80 and H9, an upward oroutward movement of spring 18 serves to close the contact betweensprings 14 and 15 and between springs III and II8. Due to the insulation8| and I28, there is no electrical connection between springs and 18andlbetween 15 and I I8, but merely a mechanical connection. Spring 18has a downturned end 85 adapted to engage the cam rise 18. As shown inFigure 7, spring 18 is normally biased so as to be out of contact withspring 11, so that the motor circuit is norm-ally open.

.The innermost three springs 82, 88 and 84 comprise the contacts forcontrolling the direction of rotation of the actuating motor. With thespring 88 in its normal position, as shown in Figure 7, it makescontactwith spring 84 and the motor will operate in clockwise direction.When the spring 88 is swung to the left, it breaks contact with spring84 and makes ,contact with spring 82, causing the motor to operate inthe counterclockwise direction. The upper or free end 88 of the spring88 extends inwardly to normally be located at an intermediate portion ofthe low portion 88 of the switch operating cam 81.

The station selector cam discs 8| are eac provided with a high cam side81 and a low cam side 88 as shown in Figure 4. These cam sides are oncircular arcs of different radii. The station-locating notch 88 islocated at one point of junction between the high and. low cam surfaces.The station-locating lug 88 carried by the forward portion of the upperend of the pawl 58 is adapted to fit in the notch 88.

The lug 88 and notch 88 are formed on the same taper, so that engagementof the lug in the notch serves to exactly locate the rotary position ofthe cam disc 8I and of the shaft 28 to which the disc is clamped duringautomatic tuning operation of the apparatus.

Referring now to Figures 1 and 6, the motor 18 has on its armature shaft8| the small drive gear 82 which meshes with the gear 88 which iscarried on an intermediate stub shaft 84, which also carries the smallgear 85. This gear 85 meshes with the large gear 88 on stub shaft 81.This shaft 81 also carries the small gear 88 which meshes with gear 88,which latter gear is mounted upon and drives the main station selectorcam shaft. 28.

The gear 88 is mounted upon shaft 28 in such manner that frictionallycontrolled slippage may occur between the gear and shaft. The gear 88 iscarried by a hub member I88 which is fixedly secured to the shaft by aset screw. The slotted spring I8I holds the gear 88 on the hub so thatthe shaft 28 normally moves with the gear 88. The slippage permitted atthis point is important in preventing damage to the parts should thegear 88 be driven in any manner while a pawl 58 engages a recess 88 in acam disc. This slip- Page also acts in usual automatic operation as afriction brake to ease the shock of sudden stoppage of the motorarmature and gear train when the pawl stops rotation of the shaft 28upon reaching the proper tuning position.

The armature shaft 8| also carries the manual drive pulley |2| which hasthe rubber friction facing I22. The manual tuning shaft I28 is carriedby the bracket 88 and extends at right angles to the main tuning shaft28 and below the latter shaft, as clearly shown in Figures 1 and 6. Therear end of shaft I 28 carries the flywheel I24. The forward end ofshaft I28 bears in the fixed sleeve I82 which has its rear end supportedby bracket I88 extending from the main bracket 88. The sliding gearsleeve I is mounted on the fixed sleeve I82 and bears directly in themain bracket 88.

The sleeve I25 is slidable relative to the shaft I28 and carries thegear I28 which may be moved into or out of mesh with the crown gear I21.The crown gear I21 is fixed on a rotatable stub shaft I28 to which alsois fixed a small gear I28 meshing with the cam disc clamping gear I88.The forward portion of the sleeve I25 is flattened on each side at I88to facilitate its manual rotation and has the flanges I8I to facilitatemanually sliding the sleeve outwardly.

The sliding clutch member I 82 is carried upon shaft I28 with which itis caused to rotate by pin I88 fitting in slot I84. This member I82 isprovided with the groove I85 to receive the clutch operating fork I88which is carried by the key bar 58 and moves with that bar. The clutch Iface I81 is adapted to engage the rubber facing I22 on wheel |2| tomanually drive the shaft 28 through the same gear train as is used inautomatic tuning.

The sleeve I88 is loosely fitted on shaft I28. It is prevented from allbut a very short longitudinal movement on shaft I28 by pin I88 fittingin slot I48, which permits a limited rotary move-- ment of the sleeve onthe shaft. The spring I4I has one end secured to sleeve I88 and theother end secured to the collar I42, which latter is secured to shaftI28 and rotates therewith. The

forward end of the sleeve I88 carries the star,

wheel I48 fixedly secured thereto. This star wheel I 48 is adapted toengage the free end of the unlatching arm I44, which latter is securedto the end portion of the latch plate 48. This arm I 44 is formed witha'downwardly extending portion I45 adapted to enact with the cam endportion I48 of the key bar 58. The lower edge of the forward portion ofthe bracket 88 has secured thereto the release spring I41 which has arise I48 adapted to. be engaged by the gear I28, as that gear is movedinto or out of mesh with the crown gear I21. The forward end of shaftI28 has the manual tuning knob I49 secured thereto.

The sleeve I82 carries at its forward end the disc I58, which is formedof insulation and serves to operate the switch assembly II1. This switchis shown in the manual tuning position in Figure 6 and in the automatictuning position in Figure 8.

The switch H1 is made up of five currentcarrying blades, and theirconnections are indicated on Figure 8. The lower spring I5| is connectedto the manual operation pilot light. The next spring I52 is connected toa power supply line of the voltage desired for pilot light operation.The middle spring I58 is connected to the automatic tuning pilot ,lightand the other sides of the two pilot lights are connected to theopposite side of the power line from spring I52. As will be seen fromFigures 6 and 8, the spring I 52 is normally biased to engage spring I5Ito light the manual tuning pilot light. When the sleeve I82 is at theleft during automatic tuning, as shown in Figure 8, the disc I58 engagesthe end I54 of spring I52, lifting it away from spring I5I and intoengagement with spring I58 to light the automatic tuning pilot light.

The upper springs I55 and I56 of switch assembly II1 are connected intothe automatic frequency control circuit in parallel with the springs H5and H8 of the key cam switch assembly 18. The end I51 is tumed under toengage an insulating spring I58 resting against spring I52. It will beseen that the circuit between springs I55 and I58 will be closed whenthe clutch assembly is in the position for manual operation and will beopen when the clutch is in the automatic position.

' The automatic frequency control circuit is no part of the presentinvention and will not be described in detail. It is merely necessary tonote that the circuit is such that with the portion of the circuit shownin Figure 8 closed, automatic frequency control does not function. Thisportion of the circuit is always closed at the clutch switch III whenthe clutch is in position for manual control, and consequently automaticfrequency control is not in operation during manual control.

The automatic frequency control circuit springs H5 and H6 on the key camswitch I3 are normally open, as shown in Figure '7, when no key ispushed in. However, as stated above, in this manual control position theautomatic frequency control circuit is out of operation due to beingclosed at switch Hi. When a key is pushed in, the cam 61 is swungupwardly and spring end 85 is lifted by cam rise I0 and the automaticfrequency circuit is closed between springs H5 and H6 regardless ofwhether the lug 90 rests on a high or low cam side of its correspondingcam disc 3|. Thus, automatic frequency control is kept out of operationeven though pushing in the key has opened the circuit between springsI55 and I56. This has been caused by the lug 49 on the key swinging keybar 50 in the clockwise direction, as seen in Figure '7, or in thecounterclockwise direction, as seen in Figure 6, which has moved thesliding clutch sleeve I32 to the left by means of fork i36 and liftedswitch III through insulated disk I50.

However, as soon as the cam disk 3I rotates to the position where thelug fits in notch 89, the bar 63 is swung further to the right as seenin Figure 7, causing the spring end to pass beyond the cam rise I0,whereupon contact is broken between springs H5 and H6; and since it isalso at this time broken between springs I55 and I56 of switch 1,automatic frequency control goes into operation to effect the finaltuning adjustment. It is important to have the switch formed by springsH5 and H6 in this circuit, as it is not desirable to have automaticfrequency control in operation when the motor drive is automaticallytuning the set. This is especially true when the station being sought isclose to a powerful station which might cause automatic frequencycontrol to operate adversely before the station sought was reached bythe motor drive.

In operating the apparatus to manually tune the set, the parts will bein the position shown in Figure 6. All keys are in the outer or releasedposition. Rotation of the manual tuning knob I48 serves to tune the setin the usual manner. The knob I49 rotates the shaft I23 which rotatesthe clutch slide I32 which has its face I31 engaging the face I22 of thepulley I2I on the armature shaft 9|. This shaft also carries the firstgear 92 of the gear train driving the main shaft 23. Thus turning themanual control knob in either direction causes a corresponding movementof the indicating means and of the radio set tuning device which isrotated by shaft I02. Shaft I02 rotates with shaft '23 due to thecoaction of gears I03 and 104.

To put the tuning device in automatic operation, it is merely necessaryto select a button and push it in until it is locked in its innerposition. Referring particularly to Figure 7, the slide 42 is locked inthis position by the detent latch 46 which is forced downwardly by thesloping rear face 45 of the slide detent- 44 and slips upwardly toengage the forward face of the latch 46 as it passes the detent. Thelatch 46 is swung upwardly by spring I64 shown in Figure 6. As the slide42 moves rearwardly, it also swings the clutch bar 60 to the left or inthe clockwise direction as seen in Figure 7. This is in thecounterclockwise direction as seen in Figure 6, and causes the clutchoperating fork I36 to move to the left in this figurewhich serves toseparate the clutch faces I81 and I22.

Movement of the slide 42 to its locked position also puts a pull uponthe spring 6i connected to the slide. The other end of the spring isconnected to the forward portion 60 of the lower end of thecorresponding pawl 58. This pull therefore swings the pawl 58 in theclockwise direction about shaft 51 as seen in Figure '1. It will beunderstood that the spring 6I is stronger than spring I2 connected tothe cam bar 63 so that bar 68 moves with the upper portion of pawl 58.The pawl 58 moves in the clockwise direction until the lug on the pawlengages the corresponding cam disc 3|.

If the lug 90 engages the high side 81 of the disc 3I, the switch cam 61is swung through only a short are. This lifts spring contact II6, I5 andI8 when the end 85 of spring I8 engages the cam rise 10 andsimultaneously shorts the automatic frequency control and the mutecontrol and closes the motor circuit. merit of cam 6! does not cause itto engage the end 86 of switch spring 83 and the motor direc tion switchremains in the position of Figure 7.

The motor is started and causes the shaft 23 and cam disc 3i to rotatein the clockwise direction as seen in Figure 7. This rotation continuesuntil lug 90 drops into notch 89 in the cam disc. This movement of pawl58 carries cam bar 63 and the switch cam 61 through a further arcuatemovement so that the downturned end 85 of switch spring I8 passes beyondthe cam rise I0 and all three switches are opened. The opening of theswitches serves to put the automatic frequency control in operation, toopen the mute circuit and to. open the motor circuit, stopping themotor. The automatic frequency control completes the tuning adjustmentof the circuit.

The operation is generally similar when the lug 90 engages the low side88 of the corresponding cam disc 3i. The automatic frequency control,mute and motor control switches are all closed in the same manner aswhen the lug 90 engages the high side 81 of the disc II. The differencein action. is that when the lug 90 engages the low side, the switch cam61 is swung sufficiently so that the cam rise II lifts the end 86 ofswitch spring 83, breaking contact with spring 84 and engaging spring 82so that the motor operates in the opposite direction. This moves thedisc 3| in the counterclockwise direction until the lug 90 drops innotch 89 when the operation is as before stated.

To resume manual tuning, it is only necessary to turn the knob I49 inthe usual manner. During the automatic turning, the clutch parts havebeen brought to the positions shown in Figure 8. The first movement ofthe knob I49 in either direction rotates shaft I23 and the star wheelI43 engages the end of the unlatching arm I44 forcing it downwardly.This'swings the latch This move- 1 bar 43 downwardly, unlatching the key4i which was last depressed. As the key slide 42 moves forwardly, or tothe right as seen in Figure 7, the tension on the spring 3| is releasedandthe pawl 53 is moved in the counterclockwise direction by the cam barspring 12 which moves that bar in the counterclockwise direction. Thisdraws the lug 33 out of the notch 33 in the cam disc 3| and releasesshaft 23 for manual operation. The lug 33 slips easily out of the notch33 due to the relative slope of their coacting faces and also becausethere is at this time no rotary thrust by the cam notch faces againstthe lug.

Also, as the slide 42 moves to the right in Figure '1, the clutch bar 53swings in the counterclockwise direction as seen in Figure 7, or in theclockwise direction as seen in Figures 6 and 8,

, under the pull of spring 55 and the clutch slide I32 is moved to theright to the position shown in Figure 8. The clutch is thus brought inoperation and the further rotation of the knob I43 serves to manuallytune the set.

The engagement between the downwardly extending portion I45 of theunlatching arm- I44 and the cam end portion I43 of the key bar 53 in theunclutched position of Figure 8, has a double function. It maintains theclutch positively in the unclutched position and also positively holdsthe switch assembly II1 with switch springs I52 and I53 in their upperposition.

The importance of the loose connection between sleeve I33 and shaft I23lies in insuring sufficient movement of the bar I44 when a key isdepressed in going from manual to automatic tuning. If the star wheelI43 were rigidly connected to shaft I23 and a key were pushed in with apoint on star wheel I43 opposite the upper end of the unlatching barI44, the movement of the bar would stop at this point so thatit couldnot be unlatched by rotation of shaft I23 and of the star wheel I43.

To change the adjustment of any or all of .the cam discs 3|, it is firstnecessary to remove the tuning knob I43. .This knob is preferably of anywell knowntype having a friction fit with the flattened end of the shaftI23 so that it is unnecessary to loosen any set screws to remove theknob, which is merely pulled oil.

The flanges I3I -on sleeve I25 are then grasped and the sleeve pulledforward, or to the left as seen in Figure 8, until the gear I23 mesheswith the crown gear I21. During this movement, the gear I26 engages therise I43 on spring I41 and the lower end of the spring thrustsdownwardly the unlatching arm I44 to release any key which may belatched inat the time. The fiat sides I33 of the sleeve I25 are thengrasped and the sleeve turned in the clockwise direction. Due to thedrive between gear I23 and the cam disc clamping gear I 33, thisrotation of sleeve I 25 serves to rotate the shaft 23 and associateddisc 3| and clamping cups 32 in the clockwise direction as seen inFigure 7. This rotation continues until the stop lug 23 engages theforward stop 21, since no pawl 53 is engaged in a notch 33 due to theautomatic release of any key that might have been latched in position.

When the stop lug 23 engages the stop 21, rotation of shaft I23 isstopped. However, the cam cup 33 and the gear I33 arenot keyed to shaftI23 and continue to rotate. This rotation continues until the axial endfaces of the cams 36 and 43 are in substantial engagement. At this time,the raised portion II! of spring I33 latches over the lug I 33 on theouter face of the gear nected to the pawl.

drawn forward to engage gear I 23 with crown this relative position. Thecam discs 3| are now no longer positively clamped in position althoughthey are still held frictionally by cups 32 so that they do not turnfreely and are not loose onshaft The next step is to press in the buttonwhich it is desired to adjust to tune to the selected station. Pressingin this button serves toautomatb,

cally tune the set to the frequency for which the cam disc 3i associatedwith the button may happen to be tuned. This will take place properly inspite of the fact that the discs are not at this time rigidly clamped.The lug 33 will now be in the notch 33 of the cam disc 3| to beadjusted. and will hold that disc against rotation. The sleeve I25 isnext turned to rotate the shaft 23, and the discs other than the discheld by the lug 33, until the indicator I1 is opposite the desiredstation frequency or until the desired station is tuned in, if the setis in operation. As many more of the discs may be adjusted as desiredmerely by pushing the buttonassociated with the disc to be adjusted andtuning in the station by means of sleeve I23.

When the desired adjustments have been made, it is necessary to againrigidly clamp all the discs 3 I. It is first necessary to release theassociated pawl lug 33 from the disc 3| last adjusted. This isaccomplished bymerely pushing in the sleeve I 25 until gear I23 engagesthe rise I 43 on the release spring I41 and thus releases the key con-After this, sleeve I25 is gear I21 and is rotated in the;counterclockwise direction. This turns shaft 23 and associated parts inthe counterclockwise direction, as seen in Figure '7, until the stop lug23 engages the rear stop 23. Continued rotation of sleeve I25 rotatesgear I33 and cam cup 33 so that the cam faces 43 are rotated relative tocam faces 33 on the cam cup 35 which is keyed to the shaft. As this.

takes place, the raised portion II2 of spring I 33 moves away from lugI33 on gear I33. This movement of sleeve I25 continues until theassembly of discs 3i and cups 32 is firmly clamped together.

The sleeve I25 is now pushed to its inner position and the knob I43replaced on shaft I23. The apparatus is now in adjustment to be tunedeither manually or automatically, as explained above.

It will be apparent that both the setting up of stations on theapparatus and its use are simple and may be readily understood by theuser of the set. The station selected by any push-button may be readilychanged in a moment without the use of tools and without removing theset panel or working in the rear of the set. i

No extra controls are necessary on the front of the set other than thepush-buttons themselves. Pushing in any station selector buttonautomatically adjusts the apparatus for tuning by the button if it isnot already in the automatic tuning position. A slight rotary movementof the manual tuning knob, as in tuning the set manually, automaticallyrestores the parts to manual, tuning position, if. they are not alreadyin that position. Consequently, the use of the apparatus involves noespecial. instructions or operation in changing from one tuning methodto the other.

While I have shown certain preferred embodiments of my invention, theseare to be under I33 to yieldingly hold the two opposite cam in v andrequirements, and I contemplate such changes as come within the spiritand scope of the appended claims.

I claim:

1. In combination with a tuning element of a radio set, a rotating driveshaft having driving connection with said tuning element, a. manuallyrotatable shaft, a driving connection between the manual shaft and driveshaft, said connection in- .0 eluding a clutch, a motor operativelyconnected to the drive shaft, a lever for starting the motor,

and means connecting the lever and manual drive clutch whereby saidclutch'is released upon moving the lever to start the motor.

[6 2. In combination with a tuning element of a radio set, a rotatingdrive shaft having driving connection with said tuning element, amanually rotatable shaft, a driving connection between the manual shaftand drive shaft, said connec-- tion including a spring-held frictionclutch, and

means whereby rotation of the manual shaft releases the spring andcauses the clutch to connect said shaft and the drive shaft.

3. In combination with a tuning element of a radio set, a rotating driveshaft having driving connection with said tuning element, a manuallyrotatable shaft, a driving connection between the manual shaft and driveshaft, said connection including a clutch, a motor operatively connectedto the drive shaft, a lever for starting the motor, means connecting thelever and manual drive clutch whereby said clutch is released uponmoving the lever to start the motor, and means whereby rotation of themanual shaft causes the clutch to connect said shaft and the driveshaft.

4. In combination with a tuning element of a radio set, a rotating driveshaft having driving connection with the tuning element, a plurality ofcam discs adjustably secured to the drive shaft, each said disc having ahigh portion and a low portion with a notch therebetween, a locking pawlassociated with each cam disc and having a portion adapted to engage thehigh or low portion and to fit in said notch, a reversible motor fordriving said dive shaft, and control switches for said motor operativelyassociated with said pawls whereby the motor is operated in onedirection when a pawl engages the high por-' tion of a disc, is operatedin the opposite direction when a pawl engages the low portion of a discand whereby the motor is stopped when a pawl engages a notch in a disc.

5. In combination with a tuning element of a radio set, a rotating driveshaft having driving connection with the tuning element, a power drivefor said drive shaft, a manual drive for said drive shaft, selectivestops for said drive shaft, and means whereby rotation of the manualdrive releases said selective stops.

6. In combination with a tuning element of a radio set, a rotating driveshaft having driving connection with the tuning element, a power drivefor said drive shaft, a manual drive for said drive shaft, selectivestops for said drive shaft, keys for actuating said stops, and meanswhereby rotation of the manual drive releases said selective stops andkeys. 7

'7. In combination with a tuning element of a radio set, a rotatingdrive shaft having driving connection with the tuning element, a powerdrive for said drive shaft, a manual drive for said drive shaft, keysfor putting said power drive in operation and selectively stopping saiddrive at predetermined points, a clutch connecting the manual drive tothe drive shaft, and means whereby actuation of a power drive keyreleases said clutch.

8. In combination with a tuning element of a radio set, a rotating driveshaft having driving connection with the tuning element, a power drivefor said drive shaft, a manual drive for said drive shaft, keys forputting said power drive in operation and selectively stopping saiddrive at predetermined points, a clutch connecting the manual drive to.the drive shaft, means whereby actuation of a power drive key releasessaid clutch, and means whereby rotation of the manual drive engages saidclutch.

9. In combination with a tuning element of a radio set, a rotating driveshaft having driving connection with the tuning element, a power drivefor said drive shaft, a manual drive for said drive shaft, keys forputting said power drive in operation and selectively stopping saiddrive at predetermined points, a clutch connecting the manual drive tothe drive shaft, means whereby actuation of a power drive key releasessaid clutch, means whereby rotation of the manual drive engages saidclutch, separate manual drive and power drive pilot lights, switchescontrolling the circuits to said pilot lights, and means associated withsaid clutch for actuating said switches.

10. In combination with a tuning element of a radio set, a rotary driveshaft having driving connection with the tuning element, a plurality ofadjustable stop means carried by the drive shaft, a manual shaft forrotating the drive shaft, means for collectively clamping and unclampingthe stop means to the drive shaft, and a sleeve upon the manual shaftfor actuating said clamping means.

11. In combination with a tuning element of a radio set, a rotary driveshaft having driving connection with the tuning element, a plurality ofadjustable stop means carried by the drive shaft, a manual shaft forrotating the drive shaft, means for collectively clamping and unclampingthe stop means to the drive shaft, and latch means carried by the driveshaft for latching the clamping means in unclamped position.

12. In combination with a tuning element of a radio set, a rotary driveshaft having driving connection with the tuning element, a plurality ofadjustable stop means carried by the drive shaft, a manual shaft forrotating the drive shaft, means for collectively clamping and unclampingthe stop means to the drive shaft, and a sleeve upon the manual shaftfor actuating said clamping means, said sleeve being slidable upon theshaft to move into and out of actuating relationship with the clampingmeans.

13. In combination with a tuning element of a radio set having anautomatic frequency control circuit, a rotating drive shaft havingdriving connection with the tuning element, a motor drive for said driveshaft, means for selectively starting and stopping the drive motor,switch means operated by said starting and stopping means whereby theautomatic frequency control circuit is out of operation when the driveshaft is in motion and in operation when the drive shaft is stopped, amanual drive for the drive shaft, clutch means for connecting the manualdrive and the drive shaft, and means whereby the automatic frequencycontrol is put out of operation when the clutch is engaged.

14. In combination with a tuning element of a radio set, a rotatingdrive shaft having driving connection with the tuning element,supplemental push button controlled tuning mechanism, detent mechanismassociated with said push buttons, and mechanical means actuated byrotation of the drive shaft to release said detent mechanism.

15. In combination with a tuning element of a radio set, a manuallyoperable rotating shaft having driving connection with the tuningelement, supplemental tuning mechanism comprising push button operatedstation selecting slides, detents for said slides, and means responsiveto manual rotation of the drive shaft to release the detent mechanism.

16. In combination with a tuning element of a radio set, a manuallyoperable rotating shaft having driving connection with the tuningelement, supplemental tuning mechanism comprising push button operatedstation selecting slides, detents for said slides, detent releasemechanism comprising an arm extending adjacent the drive shaft, and astar wheel carried by the drive shaft and adapted to engage the detentrelease arm upon manual rotation of the shaft to release the 10 detent.

ADOLPH E. GERSCH.

